Familial hypercholesterolemia

Familial hypercholesterolemia

Familial hypercholesterolemia is an autosomal dominant disorder caused by mutations in the gene encoding the receptor for low density lipoprotein (LDL). In homozygous individuals, the LDL receptor function can be absent leading to grossly reduced uptake of LDL by the liver and hence limited clearance of circulating LDL. Very high LDL levels in plasma can be detected in the neonatal period itself. Xanthomas in the skin and over tendons are quite common and may be large. Those who have less than two percent LDL receptors (considered LDL receptor negative) seldom survive beyond the second decade if untreated. Patients with LDL receptor density in the range of two to twenty five percent (considered LDL receptor defective individuals) develop atherosclerotic disease in the thirties or earlier. Prevalence of the heterozygous variety is about one in five hundred while the severe homozygous variety occurs at the rate of one in a million population.